This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Good model systems are needed to develop methods, which is certainly true of PDS. Long organic biradicals, polyradicals, and supramolecular assemblies were instrumental for development of DEER. However they are difficult to synthesize and require expertise of a good organic chemist, who should be interested in such collaborations. In our development of DQC method we could not rely on this but made a good use of few available biradicals with distances in the range of 10-30 [unreadable]. But when we needed a longer distances, we had to reach to Gunnar Jeschke for the sample. However we did find that for example DNA duplexes or some proteins can also contribute good model systems and are relatively easy to produce in house in required quantities. For the project development on time-resolved 2D-ELDOR spectroscopy, coupled with stopped flow or continuous rapid flow, we require large amounts (up to grams) of spin-labeled model proteins. For example T4 Lysozyme and Calmodulin are relatively small and stable proteins that can be expressed in required quantities with a moderate effort. In general proteins and DNA could provide us with all required distances and a variety of spin configurations. Furthermore, they are much more relevant to our research.